Re: [PATCH] overlay: ensure that existing phandles are not overwritten

[David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>]

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On Fri, Apr 28, 2023 at 08:09:06PM +0200, Uwe Kleine-König wrote:
> Hello,
> 
> On Wed, Apr 26, 2023 at 12:02:31PM +0200, Uwe Kleine-König wrote:
> > -static int overlay_adjust_node_phandles(void *fdto, int node,
> > -					uint32_t delta)
> > +static int overlay_adjust_node_phandles(void *fdto, int nodeo,
> > +					uint32_t delta, void *fdtbase, int basenode, uint32_t *phandlemap)
> >  {
> > -	int child;
> > +	int childo;
> >  	int ret;
> > +	const fdt32_t *phandlebase;
> > +	int phandlebaselen;
> >  
> > -	ret = overlay_phandle_add_offset(fdto, node, "phandle", delta);
> > -	if (ret && ret != -FDT_ERR_NOTFOUND)
> > -		return ret;
> > +	/*
> > +	 * If the base fdt has a phandle already reuse the value to not break
> > +	 * references that already exist in the base fdt.
> > +	 */
> > +	if (fdtbase) {
> > +		phandlebase = fdt_getprop(fdtbase, basenode, "phandle", &phandlebaselen);
> > +		if (!phandlebase && phandlebaselen != -FDT_ERR_NOTFOUND)
> > +			return phandlebaselen;
> > +		if (!phandlebase) {
> > +			phandlebase = fdt_getprop(fdtbase, basenode, "linux,phandle", &phandlebaselen);
> > +			if (!phandlebase && phandlebaselen != -FDT_ERR_NOTFOUND)
> > +				return phandlebaselen;
> > +		}
> > +		if (phandlebase && phandlebaselen != sizeof(*phandlebase))
> > +			return -FDT_ERR_BADPHANDLE;
> > +	}
> >  
> > -	ret = overlay_phandle_add_offset(fdto, node, "linux,phandle", delta);
> > -	if (ret && ret != -FDT_ERR_NOTFOUND)
> > -		return ret;
> > +	if (fdtbase && phandlebase) {
> > +		ret = overlay_phandle_set(fdto, nodeo, "phandle", fdt32_to_cpu(*phandlebase), phandlemap);
> 
> Compiling that on Ubuntu stable emits a warning here that phandlebase
> might be uninitialized (see
> https://github.com/ukleinek/dtc/actions/runs/4831386302/jobs/8608771064).
> 
> While looking into that, I think the code is correct, but can be
> simplified by using fdt_get_phandle() instead of open coding it. I'll
> rework the code and test a bit more. So please don't apply this version
> of the patch.

Ok, will do.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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